For some reason, it kills to go down into a center split. I'm perfectly straight, I lower myself down as so, and thats when it feels like a joint is about lock into or break. I have no problem doing butterfly stretches...most of time. The first time I tried a center split, it didnt hurt my joint at all and I went down lower but now it just kills!
Your problem is that, like you said, you're perfectly straight. That pain you're feeling is the top head of your femur jamming into your hip socket. You need to rotate your pelvis to provide room for the femur to slot in nice and tidy. Do this by sticking your butt to the rear a bit more. Let me know if you need a photo explanation. Hope this helps!
Yeah I think I need a photo explanation because I'm like sticking my butt out but the femur is still jamming into the hip socket.Should my legs be on my side completely or is it fine to bring them in a little bit like a wide V?
Then it most probably is as I thought. I'll post a photo shortly demonstrating how to rotate your pelvis. In the meantime this illustration may help: